The main issue here is supply. If there were enough houses then we wouldn't have so many threads suggesting creative ways of taking houses away from people. Making the system punitive enough to free up large numbers of houses would lead to a lot of very unhappy players. We already have to jump through hoops to keep our houses and making small FCs less viable would be unfair on people who simply want a FC for personal friends or family. I certainly wouldn't like to see any system that encourages FCs to spam invite newbies just so they can keep their house.

It's worth remembering that Japanese servers are smaller than the E.U. or North American ones. I would hope that the Devs are aware that this is an issue that disproportionately affects players on E.U. and the U.S.A. servers, but I do wonder if the fact that this is a lesser problem for Japanese players might be something to do with the apparent belief that adding a few more wards will sort everything out. On a server like Balmung, adding Ishgard wards is going to have as much effect as a drop of water on a bucket of hot sand.

We already have instanced housing in the form of apartments but they are unattractive due to their small size and lack of an outdoors. If a FC could buy a large apartment with access to a workshop via their Grand Company and have somewhere to garden along with members being able to have personal rooms, then I think there would be less demand for housing in the wards. It would be nice for individuals to be able to upgrade their apartments to a larger size too.

Personally, I think improving apartments or introducing a new type of instanced housing that gives you access to a garden alongside the existing wards would be a better way to go than tweaking the frankly horrid system we have at present. I do understand the frustration when shell FCs take over a large number of houses, but all the proposals to curb this by making it even harder for people to keep a house once they get one, are likely to harm individual home owners far more.
The only change I would like to see is making it impossible for an individual to hold more than one FC and one personal house per server, I can't see any problem with that.